CHEMMEM Report Summary

Final Report Summary - CHEMMEM (A chemical approach to understanding the role of membranes and membrane transport in cell division)

Cell division is an important fundamental biological process required for life, growth and development. It requires the coordinated action of many different cellular machines and regulators. Although we have known that cells divide since the concept of the cell was first established, there are many outstanding mechanistic questions, especially in cytokinesis, the final step where cells physically divide. The objective of this proposal was to understand the roles of membranes and membrane trafficking during cytokinesis.Although massive membrane rearrangements occur during cell division, almost nothing is known about the role lipids play during this process. We used mass spectrometry to determine if the lipidome changes in dividing cells and at a division site (the midbody) and found that only very specific lipids with specific side chains accumulate (Atilla-Gokcumen, Muro et al., Cell 2014). Using AFM in collaboration with Dr. Sergi Garcia-Manyes at King’s, we demonstrated differences in the mechanical properties of live dividing cells and their isolated lipids relative to non-dividing cells. In parallel, we systematically used RNAi to knock down lipid biosynthetic enzymes and identified enzymes required for division, which highly correlated with lipids accumulated in dividing cells. Having determined the nature of lipids involved in cell division and their biosynthetic enzymes, the next steps are to understand their functions. Lipids can have structural roles or can be involved in signal transmission, and our data suggest that they do both. To further investigate the lipids’ biological roles, we are using chemical and cell biology approaches as well as biophysics and have gained new insights into the biological roles of some specific lipid families.Membrane trafficking is needed during cytokinesis to transport protein and lipid cargoes to their destinations in the division machinery, but most of the specifics are unknown. We reported that the clinically used drug Prazosin is a small molecule inhibitor of endocytic sorting and cytokinesis (Zhang et al., PNAS, 2012). Prazosin exerts this effect through a GPCR, the dopamine receptor D3 and, using Prazosin as a tool compound, we showed that DRD3 is a regulator of endocytic sorting. This is a new biological function for a GPCR and we are working to understand in more detail how DRD3 participates in endocytosis and cytokinesis.